Gas sensor arrangement

ABSTRACT

This invention relates to a gas sensor arrangement in which one or more gas sensors ( 4 ) are placed into rooms for monitoring or measuring gas or vapor concentrations or mixtures, a (diffusion body ( 5 ) is placed in front of the gas sensors ( 4 ), the responsiveness of the gas sensors, is impaired by structural) (design or contamination and/or the gas atmosphere is static. The sensor ( 4 ) or sensors ( 4  l to  4 .n) are placed in, on. or in front of a duct ( 1 ) located in the room and thus are within the flow area of said duct ( 1 ), and a flow is present in the duct ( 1 ) during measuring or monitoring. The duct can be artificially heated using a heater ( 6 ) to generate this flow

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention This invention is particularly suited for gas sensors with an upstream diffusion barrier whose responsiveness is impaired by structural design of contamintation, or which are primarily used in state gas atmospheres

[0002] 2. Background Art

[0003] When gases or vapors reach the sensor(s) by diffusion through porous bodies, it is known that diffusion barriers with diffusion gradient are formed that impair gas exchange, for gas diffusion through such barriers is determined by the pressure difference.

[0004] Thus small measuring ranges and the required high responsiveness can no longer be achieved using conventional gas sensor arrangements, especially when diffusion barriers exist or in static gas atmospheres.

SUMMARY OF THE INVENTION

[0005] It is the problem of this invention to improve the dynamic properties of the gas and vapors under the conditions mentioned above. This problem is solved by the characterizing features of claim 1 while advantageous embodiments are the subject of the dependent claims. Claim 8 describes an alternative use.

[0006] The gas sensor arrangement of the invention in which one or more gas sensors are configured to monitor or measure concentrations of gas, vapor or mixtures in rooms and in which the gas sensor are located behind an upstream diffusion barrier so that their responsiveness in impaired by structural design or contamination and/or the gas atmosphere is stati, involves that the sensor(s) are located in on and/or in front of a duct. i.e. in the flow area of this duct, and that a flow is present in this duct when the sensor(s) are measuring or monitoring Most preferably, the duct extends from down upwards.

[0007] The flow can advantageously be generated by the natural difference in temperature, and/or the duct is artificially heated using a heater.

[0008] The invention utilizes the finding from practical measurements that, even for small gas concentrations to be measured signal change in remote measuring heads operating on the diffusion principle is clearly greater when the flow changes from near zero to low than whenn the flow changes from low to high.

[0009] In a preferred embodiment, the duct is a tube with at least one lateral opening, most simply a hole, through which the sensor has gas contact.

[0010] This module can easily be integrated in a casing that houses measuring and evaluation equipment. The upper and lower ends of the tube pass through the walls of the casing. The sensor may easily comprise an upstream diffusion body. In addition, this arrangement also allows for using dissipated energy from electronic or electric components inside the casing for heating the duct artificially.

BRIEF DESCRIPTION OF THE DRAWING

[0011]FIG. 1 is a partial cross-sectional view of a gas sensor arrangement, according to the invention.

DETAILED DESCRIPTION OF THE DRAWING

[0012] An embodiment of the gas sensor arrangement that is particularly suited for use as a conflagration gas detector in power stations is described below with reference to the figure.

[0013] The duct 1 is tube-shaped and placed in a casing 7 together with measuring and evaluation equipment. The tube ends pass through the upper and lower casing walks so that gases and vapors can flow through the tube without obstruction. The tube comprises a lateral opening 2, preferably a hole, through which the sensor has gas contact. A diffusion body 5 that has to be penetrated by the gas or vapor for measuring/monitoring is placed in front of the sensor 4. The dissipated energy from electronic or electric components in the casing 7 is used to artificially heat the tube used as duct 1 with the heater 6, which simultaneously cools the electronic or electric equipment. At the same time, a constant flow is generated in the tube during measuring or monitoring that accelerates gas diffusion and gas or vapor exchange at the sensor4. The responsiveness of sensor 4 is considerably increased in this way

[0014] The sensor arrangement according in the invention can also be transferred to measurements or monitoring in water where responsiveness is changed by bubbles that form on water electrodes. This arrangement would compose an immersion tube instead of the duct and, for example, if water electrode instead of the gas sensor. When a constant flow is generated in the immersion tube, for example, by artificial heating bubble deposition on the water electrode that is in the flow area of the immersion tube is prevented or reduced, thus considerably increasing responsiveness. 

We claim:
 1. A gas sensor arrangement in which one or more gas sensor are placed into rooms for monitoring or measuring gas or vapor concentrations or mixtures, a diffusion barrier is placed in front of the gas sensor the responsiveness of the gas sensor is impaired by structural design or contamination and/or the gas atmosphere is static, characterized in that the sensor (4) or sensor (4.l to 4.n) are placed in, on or in front of a duct (1) located in the room and thus are within the flow area of said duct (1), and that a flow is present in the duct (1) during measuring or monitoring
 2. The gas sensor arrangement according to claim 1 , characterized in that the duct (1) extends from down upwards.
 3. The gas sensor arrangement according to claim 1 , characterized in that the duct is artificially heated using a heater (6).
 4. The gas sensor arrangement according to claim 1 , characterized in that the duct (1) is designed as a tube with at least one lateral opening (2), preferably a hole, through which the sensor (4) has gas contact.
 5. The gas sensor arrangement according to claim 1 , characterized in that the duct (1) passes through a casing (7) that houses measuring and evaluation equipment, is open at the bottom and at the top and that the sensor (4) is located inside the casing (7) and is connected to the inside of the duct (1) via an opening (2).
 6. The gas sensor arrangement according to claim 4 or 5 characterized in that a diffusion body (5) that has to be penetrated by the gas or vapor for measurement or monitoring is placed in front of the sensor (4).
 7. The gas sensor arrangement according to claims 3 and 6, characterized in that the dissipated energy from electronic or electric equipment inside the casing (7) is used for artificially heating the duct (1).
 8. Use of a gas sensor arrangement according to any one of claims 1 through 7 for measuring and monitoring in water wherein the duct is designed as an immersion pipe and the sensor(s) are water electrodes. 